My present invention relates generally to apparatus for deforming a workpiece and more particularly to apparatus for continuously extruding a rod of indefinite length to produce a wire of indefinite length.
It will be understood by those skilled in the art that my present invention is an improvement in my prior inventions disclosed in U.S. Pat. Nos. 3,740,985, issued June 26, 1973 (reissued May 4, 1976 as U.S. Pat. No. Re. 28,795) and No. 3,985,011, issued Oct. 12, 1976, and in particular is an improvement in my invention disclosed in the latter patent. Accordingly, it will be further understood that the disclosure of U.S. Pat. No. 3,985,011 is hereby incorporated herein by reference and only the improvements over my invention disclosed in U.S. Pat. No. 3,985,011 are disclosed and claimed herein. Still further, it will be understood that my present invention may be utilized for the continuous extrusion of tubing of larger diameter and larger wall thickness into tubing of smaller diameter and smaller wall thickness, particularly upon the apparatus of my U.S. Pat. No. 3,985,011 being modified in accordance with my invention of U.S. patent application Ser. No. 449,561, filed Dec. 13, 1982, now U.S. Pat. No. 4,523,444, entitled METHODS OF AND APPARATUS FOR CONTROLLING THE GAP BETWEEN A MANDREL AND DIE DURING EXTRUSION, and as taught therein. Accordingly, it will be understood that while my present improved invention is taught in terms of extrusion of rod into wire, such invention may be utilized to extrude tubing when modified in accordance with my above-noted pending patent application. Hence, it will be understood that as used herein the expression "elongated workpiece" is used to mean, inter alia, rod of indefinite length or tubing of indefinite length and of larger diameter and larger wall thickness, and the expression "elongated product" is used to mean inter alia, wire and tubing of smaller diameter and smaller wall thickness.
While the inventions of my above-mentioned prior patents perform reasonably well, instability has been experienced in maintaining relative geometric shape and coaxial alignment between the input rod, bore of moving chamber provided by the moving gripping element members and the bore of the extrusion die. Such coaxial misalignment can cause undesirable marking, cutting and shaving of the rod. Shaved particles can lodge between the moving gripping element members and cause leakage of the pressure medium or hydrostatic fluid and damage of the extrusion die O.D. Also, in extreme cases, it has been found that the bore diameter of the moving chamber provided by the moving gripping element members was larger than the rod diameter allowing slippage between the gripping element members and rod causing interruption and occasionally cessation of rod advancement and hence cessation of extrusion. Accordingly, it has been found that there is a need in the art of improvements for maintaining the rod, the centrally apertured chamber, and the extrusion die in coaxial alignment with the center-line of the extrusion apparatus during extrusion of the rod and for maintaining the centrally apertured chamber in circular geometric shape.